Liquid crystal display devices normally consist of a light source that is placed at the back surface of a liquid crystal panel. Conventional light sources often have a cold cathode ray tube or other lamp as the emission means, but light sources that use a light-emitting diode or other semiconductor element as the light-emitting means are now used for practical purposes (for instance, refer to JP Unexamined Patent Application (Kokai) 2001-92,414, and JP Unexamined Patent Application (Kokai) 2001-332,764).
On the other hand, a typical color display system for liquid crystal display devices is a field sequential display system (refer to JP Unexamined Patent Application (Kokai) 2002-287,112 and JP Unexamined Patent Application (Kokai) 2002-318,564. Colors are displayed by such a system as a result of light being radiated by emission means corresponding to each color of R (red), G (green), and B (blue) and, in synchronization with this radiation, an image corresponding to the radiated colors is displayed on a liquid crystal panel. For instance, a frame period, which is the smallest unit necessary for displaying one image, is split into three subfields and emission is performed in the order of R→G→B in accordance with the respective subfield. As a result, an observer can watch a moving picture on the display screen by color display.
The intention of using a semiconductor element such as a light-emitting diode as the emission means is to reduce power consumption of the display device and to minimize the amount of heat generated. However, field sequential systems are known to pose a problem in terms of a color disruption that is attributed to mistiming of emissions, and the like. A system of sequential repetition has been proposed in order to solve this problem whereby the frame period is further subdivided, for instance, divided into six subfields, and one of the three primary colors of R, G, and B is selected and radiated (refer to JP Unexamined Patent Application (Kokai) 2003-280,614).
Nevertheless, there is a need for further modification because there is no effective means for the efficient use of light output from an emission means in order to lower the energy consumption while maintaining a relatively strong brightness. For instance, the display switching speed of the liquid crystal display is not fast enough to follow the switching between the emission means when the above-mentioned subfield is further divided into six fields; therefore, it is very difficult to realize a practical display device.
Thus, an object of the present invention is to provide an improved display device with which the above-mentioned problems can be solved.